In recent years, with the widespread use of a wireless LAN (IEEE802.11 standard), a large-scale wireless LAN network system is being increasingly built in a public network and corporate network. Accordingly, it is studied to shift from a method of installing access points (AP), for example, setting and installing wireless LAN base station apparatuses individually to a method whereby an AP control apparatus connected to a plurality of wireless LAN base station apparatuses, for example, a wireless LAN base station control apparatus performs automatic settings, failure management, collection of statistical information of the wireless LAN base station apparatuses collectively. Such a study is being conducted by IETF (Internet Engineering Task Force) which is an international standardization organization and IEEE802.11 working group or the like, and the planning of the standardization is underway.
Consequently, it is studied to perform bridge processing between a wireless LAN frame (802.11 standard) and an Ethernet (registered trademark) frame by a higher AP control apparatus instead of the wireless LAN base station apparatuses, and an architecture is studied in which opening/closing ports for authentication are also shifted from the wireless LAN base station apparatuses to the AP control apparatus. In such an architecture, the CAPWAP working group of IETF proposes an LWAPP (light weight access protocol) as one of protocols for managing APs. According to this LWAPP, the AP control apparatus performs control such as automatic setting of setting information, failure management, statistical information collection and setting of encryption key information on the wireless LAN base station apparatuses.
The communication system proposed here specifies communication using an Ethernet (registered trademark) tunnel between the AP control apparatus and the wireless LAN base station apparatuses to perform this control (see Non-Patent Document 1). This Ethernet (registered trademark) tunnel is determined by a set of transmission source MAC address and destination MAC address. The LWAPP describes that the MAC address of the transmission source interface is set as the transmission source MAC address of the Ethernet (registered trademark) tunnel, and the MAC address of the destination interface is set as the destination MAC address.
Conversion between a WLAN frame of user traffic and an Ethernet (registered trademark) frame is performed at an AP in a general wireless LAN system. However, as the LWAPP includes description of “Centralization of the bridging”, the conversion between the WLAN frame and the Ethernet (registered trademark) frame is performed at the AP control apparatus in a centralized manner, and the WLAN frame (hereinafter, referred to as an 802.11 frame) is encapsulated with an Ether header and communicated between the AP and the AP control apparatus. In this case, the AP does not perform any complicated work such as header conversion and only removes encapsulation for the communication terminal, that is, only removes the Ether header and transmits the frame to the terminal side. Furthermore, as for the frame to be transmitted from the communication terminal to the reception network side, the 802.11 frame is only encapsulated with the Ether header and transmitted to the network side, and therefore there is a merit that processing of the AP becomes quite simple.
Non-Patent Document 1: IETF draft draft-ohara-capwap-lwapp-00.txt “Light Weight Access Point Protocol”